FRPFiber Reinforced Pervious

“Pervious in Paradise”National Pervious Concrete Pavement AssociationSan Diego, CAAugust 5, 2014

“Pervious in Paradise”National Pervious Concrete Pavement AssociationSan Diego, CAAugust 5, 2014

Pervious concrete is designed to allow storm water to pass through it, and more slowly be distributed into a site

drainage system.

INTRODUCTION

INTRODUCTION

The void structure is achieved by removing the sand/cement/water paste fraction of the mix. What remains is cement-covered coarse aggregates stacked together, allowing 15% to

30% voids.

INTRODUCTION

The very void system that allows pervious to be permeable reduces its strength – paste is stronger than air!

The constant challenge is a durable balance between permeability and strength.

INTRODUCTION

Owners, designers, contractors and researchers continue to search for methods and materials that will add back toughness and durability to all types

of pervious pavements.

ASTM

Synthetic Fiber History and Background►Founded in 1978, FORTA Corporation was the first to bring synthetic fiber technology to the U.S. and has pioneered manufacturing, testing and projects around the world.

►Over 30 years of research, practice and experience have helped FORTA ® develop new applications and technology.►FORTA® developed a fiber-characteristic formula to help guide fiber parameters for new applications.

FIBER: BACKGROUND

ASTM

Fiber Characteristic Formula: 4-C’s►CONFIGURATION

Fiber shape and configuration affect both performance and mixability

►CHEMISTRYFiber make-up determines strength and long-term durability

►CONTENTSDosage affects performance and user friendliness

►CORRECT LENGTHFiber length affects performance, mixability and friendliness.

FIBER: BACKGROUND

ASTM

FIBER: PERVIOUS

Fiber Development for Pervious Concrete

ASTM

Optimum Fiber Characteristics for PerviousC - CONFIGURATION

blend of heavy-duty macro-filaments with small amount of micro-fibrillated.

C - CHEMISTRYhigh-strength co-polymer and recycled polypropylene

C - CONTENTS2.5 to 7.5 lbs. / cu. yd.

C – CORRECT LENGTH1 ½” – 2 ¼”

FIBER: PERVIOUS

ASTM

FORTA®

FERRO-GREEN®

► Unique blend of twisted-bundle macro fibers and recycled polypropylene

► Specifically designed to mix, distribute and finish well in pervious concrete

► Dosage ranges from 0.17% to 0.5% by volume

-2.5 lbs. / cu. yd., curbs and sidewalks

-5.0 lbs. / cu. yd., light-duty car park lots-7.5 lbs. / cu. yd., high traffic paving lanes

FIBER: PERVIOUS

ASTM

Various research programs have been performed for low dosages of micro fibers.

FORTA® research focused on potential enhancements to toughness and durability offered by synthetic macro fibers.

FRP ResearchFRP RESEARCH

ASTM

Durability research program► University of Missouri – Kansas City

► Dr. John Kevern, P.E. Assistant Professor of Civil Engineering

► March 2013► “Investigating the Durability of Pervious Concrete Reinforced with FORTA® FERRO-GREEN® Macro Fibers”

FRP RESEARCH

ASTM

Goal was to determine optimum fiber length and dosage to enhance durability issues:► Tensile strength

► Abrasion resistance

► Freeze-thaw durability

FRP RESEARCH

ASTM

Test Mix Design (per cubic yard)

Cement 573 lbs.

3/8” crushed limestone 2175 lbs.

River sand 165 lbs.

Water 195 lbs.

High-range water reducer 4oz./cwt

Air entrainer 2oz./cwt

Hydration stabilizer 6oz./cwt

*Design void content 25%

Fiber Parameters

Type synthetic macro blend

Length 1-1/2”, 2-1/4”

Dosages 2.5, 5.0, 7.5 lbs. / cu. yd.

FRP RESEARCH

ASTM

Compressive (ASTM C39)

7 day 28 day

Control 2188psi 2423psi

Fiber Ave. 2240psi 2496psi

► As expected. No fiber change to compressive strength once densities were equalized

FRP RESEARCH

ASTM

Splitting Tensile Strength (ASTM C496)

► Higher fiber dosage – higher strength

► Longer fiber length = higher strength

► 7.5 lb. / cu. yd. of 2.25” fiber = +44%

FRP RESEARCH

ASTM

Raveling Resistance (ASTM C1747) FRP RESEARCH

Raveling specimens before and after testing

► 4”diameter x 4” high cylinders► LA abrasion method► Fiber addition reduced abrasion losses by 5% to 15%► No trend re: fiber dosage or length

ASTM

Surface Wearing (ASTM C944)

Surface abrasion device

FRP RESEARCH

► No clear trend re: fiber dosage or length► All fiber mixes showed considerable abrasion improvement – 30% to 65% reduction in abraded losses► Most common cold-weather durability issue = snow plow abrasion► Fiber contribution to this durability issue is significant

ASTM

Freeze Thaw Resistance (ASTM C666)

Freeze-thaw apparatus

FRP RESEARCH

► Specimens tested under worst-case scenario – completely saturated condition in rapid freeze thaw cycles► Test completed at 300 cycles or 15% mass loss

ASTM

Freeze Thaw Durability Factor Results

Mass Durability RDM Durability

Control 53 14

2.5lb./1.5” 38 125.0lb./1.5” 53 7

7.5lb./1.5” 85 21

2.5lb./2.25” 89 40

5.0lb./2.25” 91 41

7.5lb./2.25” 96 44

► Higher retained mass = higher durability

► Higher relative dynamic modulus factor = higher durability

► Long fiber mixes = 3 times the RDM durability

FRP RESEARCH

ASTM

Freeze Thaw Results

► The plain and 2 low-dosage, short fiber mixes failed prior to the 300 cycle regimen, however the failure mode was completely different

Control failed at 187 cycles with complete loss of integrity

1-1/2” fiber @ 2.5lbs./cu. yd. failed at 133 cycles in single-crack mode

1-1/2” fiber @ 5.0lbs./cu. yd. failed at 188 cycles yet retained integrity

FRP RESEARCH

ASTM

Freeze Thaw Results

► The high-dosage 1-1/2” fiber mix and all dosages of 2-1/4” fiber reached 300 cycles with ease. The condition of the specimens improved dramatically with increased dosage.

1-1/2” fiber @ 7.5lbs./cu.yd. at 300 cycles

2-1/4” fiber @ 2.5lbs/cu.yd. at 300 cycles

2-1/4” fiber @ 5.0 lbs./cu.yd. at 300 cycles

2-1/4” fiber @ 7.5lbs./cu.yd. at 300 cycles retained almost complete integrity

\

FRP RESEARCH

ASTM

UMKC Research Summary

► Fibers = no reduction to compressive strength

► Fibers = considerable increase to tensile strength +44% at 7.5lbs. of 2-1/4”

► Fibers = considerable reduction of raveling and abrasion for both fiber lengths and all dosages

► Fibers = dramatic increase to freeze-thaw durability with long fibers @ 3x durability factor

► Fibers = tremendous over-all improvement to pervious concrete durability

\

FRP RESEARCH

ASTM

Current Performance Levels and Fiber Recommendations

Level 1: Shrinkage crack control1.0 lb. / cu. yd., short ½” – ¾”, monofilament

Level 2: Shrinkage crack control, stability contributions1.5 lb. / cu. yd., ¾” -1 ½”, fibrillated-net recycled

polypropylene

Level 3: Crack control, considerable stability enhancements, improved post-crack toughness and durability

2.5, 5.0 or 7.5 lbs. / cu. yd., 1 ½”-2 ¼”, twisted-bundle macro-filament blended with recycled polypropylene

FIBER: SUMMARY

ASTM

FRP: CONCLUSIONS

► Historic perception of pervious concrete has been question of long-term durability

► Project use and laboratory research have offered considerable evidence that macro synthetic fibers can improve durability

► Aside from changes to materials and practice, fibers represent the best opportunity to improve pervious concrete pavements.

Thank You!

FORTA Corporation100 Forta Drive

Grove City, PA 16127800-245-0306

www.forta-corp.com